Thomas a



(No Model.)

T. A. EDISON.

SYSTEM 0F BLEGTR-IG LIGHTING.

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THOMAS A. EDISON, OF MENLO PARK, NEW JERSEY, ASSIGNOR TO THE EDISON ELECTRIC LIGHT COMPANY, OF NEW YORK, N. Y.

SYSTEM OF ELECTRIC LIGHTING.

SPECIFICATION forming part of Letters Patent No. 248,422, dated October 18, 1881. i

' Application tiled January 31,1881. (No model.) i

To all rwhom it may concern: Y

Be it known that I, THOMAS A. EnrsoN, of Menlo Park, in the county of Middesex and State ot' New Jersey, have invented a new and useful Improvement in Systems ot" Electric Lighting; and I do hereby declare that the following is a full and exact description ot the same, reference being had to the accompanying drawings, and to the letters ot' reference marked thereon.

In systems of electric lighting wherein a large number of lamps are supplied with current from one generator, or from a number of generators at a central station, the amount ot' energy generated should be proportioned to the demand-that is, as the number of lamps is increased a greater amount ot' energy should be supplied, and vice versa-in order that the light furnished by each lamp may be kept nearly uniform irrespective ot' the number in use.

In prior applications I have shown various means and methods otA so regulating the generative capacity of the generators, and theinvention in this case relates to another method therefor, the object being to furnish means whereby when one or a number of lamps are thrown into circuit the act ot" so throwing them into circuit shall also automatically, and at the same time, put into operation means whereby the generative capacity of the generator shall be proportionately increased.

The invention is more particularly applicable to systems wherein there are a number of lamps, with their multiple-arc circuits, which may be connected in one sub-system, which it is practicable to control by one circuit-closer, as, for instance, 0n ships where the system may be divided into sub-system`s,one for the cabin, one for the deck, and so on, as may be desired, or in cities, where the street-lamps may be arranged in special circuits or sub-systems. To accomplish this, main conductors, as usual,lead from the generator, and across them, in groups or sub-systems, are a number of multiple-are or derived circuits containing lamps, one circuit-closer being arranged to control the circuit for one lamp or an entire group.

The field-magnet coils of the generator are led, one at each group, arranged to be closed by the circuit-closer controlling the circuit of that group.

In each brauch or derived circuit ofthe lieldcoils is a resistance so proportioned that as a grou pis turned on or used only such an amount of current is allowed to tlow through the iieldcoils as will suffice to give or to increase the degree of magnetic intensity ofthe field-mag nets, so as -to insure the generation of just enough current to properly supply that group. The act ot turningon the group tirst used closes the circuit to the eld-coils, so that the generator is energized just when and to thatJ extent that call is made upon it. It', now, another group be turned on, another multiple-arc or branch circuit for the tield-coils is closed. As these circuits to the held-coils are derived circuits the closure ot' two diminishes the net resistance ot the tield-coil circuit, permitting a tlow of increased current through the. ieldcoils, increasing the magnetic intensity of the fieldmagnets, and, of course, the generative capacity ot' the generator. This is illustrated in the drawing, wherein G is a generator composed of the field-magnets F M, with polar extensions l? P, between which is the revolving armature A, on whose commutator take the commutatorsprings C C. From the generator lead the main conductors l 2, across which are the groups of multiple arcs 5 6, containing lamps L. Thecoilsofthefield-magnetsareconnected on one side by a wire, 7, directly to 1 of the main conductors. Upontheotheraconductor, 3, leads to the most remote group, from which branch conductors lead at each group, as shown at 8 and 9, each branch having a resistance, It or R. Each group is provided with a key or switch, S, constructed, as shown, so as to close simultaneously the circuit ot' its group and a branch circuit to the eld.- 3 8 S, group 5 l 7, forms one, and 3 9 S, group 6 1 7, a second derived or multiple-arc circuit for the tieldmagnet coils. It', now, S of group 5 be closed it closes the circuit ot' 5, and simultaneously one circuit for F M, giving the proper degree ot magnetization to P P for the work to be performed. If, then, S of group 6 be closed it puts into circuit the lamps of that group, closing simultaneously the next derived circuit, thus diminishing the total resistance of the field-circuit, increasing, consequently, the current therein and the degree of' magnetization of P P, strengthening the generator to meet the increased demand upon it.

rlhe resistances lt R are proportioned, as before stated, so that only the needed amount of current to properly energize the field-maga nets will be permitted to pass through the field-circuit. As groups are turned off it is evident a reverse operation takes place.

In addition to the multiple-are circuits ot' the field described, another, l0, may be used, having a resistance, R", which circuit is constantly closed, so thata certain definite amount of current may be permitted to pass through the field-coils, but not sufcient to bring the lamps up to the standard candle-power, the closure of a branch circuit suflicing to throw enough current through such coils to bring the light up to the required standard. Only one generator and two groups are shown, as they are sufficient to show the principle of the invention; but it is evident that any needed number of generators and groups or single lamps may be used with the same automatic regulation of generative force.

l. The combination, with a generator and a lamp or group of lamps, ot' means for automatically regulating the generative force of the generator by regulating the current, energizing the eld-of-force coils simultaneously with controlling the lamp or group of lamps, sub stantially as set forth.

2. The combination, with a generator and a lamp or group of lamps, of multiple-arc or derived circuits for the ield-of-force coils, one such circuit being connected to each group of lamps, substantially as set forth.

3. The combination, with a generator and a lamp or group of lamps, ot' multiple-arc orderived circuits for the tield-of-force coils, one such circuit being connected to each lamp or group of lamps, and controlled by the circuitcloseror switch of such lamp or group ot' lamps, substantially as set forth.

4. lhe combination, with a generator and a lamp or group ot lamps, ot' multiple-arc or derived circuits for the ield-otforce coils, one for each lamp or group of lamps, and a constant closed multiple-arc or derived circuit, substantially as set forth.

This specification signed and witnessed this 20th day of January, 1881.

THOS. A. EDISON.

Witnesses:

WM. CARMAN, Otras. CLARKE. 

